Bit

ABSTRACT

A rotatable or non-rotatable bit for road milling, mining, and trenching equipment that includes a substantially solid body and a substantially solid, generally cylindrical shank depending from a bottom of the body. The bit can be a unitary piece or can include a forward portion friction welded to a forward end of the body. The forward portion is machined after being friction welded and/or the unitary piece is machined to include an outer profile and a bore having a bore termination with a flat distal end and an arcuate portion curving into the sidewall of the bore. The bore is adapted to receive a bit tip insert complementary shaped to the bore of the forward portion.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to U.S. Provisional Application No. 62/864,241, filed Jun. 20, 2019, claims priority to and is a continuation-in-part of U.S. Provisional Application No. 62/476,194, filed Mar. 24, 2017, claims priority to and is a continuation-in-part of U.S. Non-provisional application Ser. No. 15/927,795, filed Mar. 21, 2018, and claims priority to and is a continuation-in-part of U.S. Non-provisional application Ser. No. 15/960,749, filed Apr. 24, 2018, to the extent allowed by law and the contents of which are incorporated herein by reference in their entireties.

TECHNICAL FIELD

This disclosure relates generally to a bit with a friction welded bit body used in mining, trenching, and milling equipment, a unitary bit used in mining, trenching, and milling equipment, and/or the use of a 4340 steel member of a bit and a nickel bearing braze alloy to attach a tungsten carbide insert to the 4340 steel member.

BACKGROUND

Road mining, trenching, and milling equipment utilizes bits and/or picks traditionally set in a bit assembly. Bit assemblies can include a bit and/or pick retained within a bore in a base block. Bit assemblies can also include a bit and/or pick retained by a bit holder and the bit holder retained within a bore in a bit holder block, hereinafter referred to as a base block. A plurality of the bit assemblies are mounted on an outside surface of a rotatable, cylindrical drum, typically in a herringbone, V-shape, or spiral configuration. A plurality of the bit assemblies can also be mounted on an endless chain and plate configuration or on an outer surface of a continuous chain. In one embodiment, the bit body of the present disclosure includes a high compression and high tensile strength forward end member that is friction welded to the bit body and machined to the desired profile. In another embodiment, the bit body of the present disclosure is a unitary piece that includes a forward end member. The bit body also includes a cutting tip insert that is mounted in a recess in the forward end member of the bit body. The cutting tip insert can include a top portion that can be designed with a generally conical, parabolic, angular, and/or somewhat flattened radius style tip profile. The combinations of bit assemblies have been utilized to remove material from the terra firma, such as degrading the surface of the earth, minerals, cement, concrete, macadam or asphalt pavement. Individual bits and/or picks, bit holders, and base blocks may wear down or break over time due to the harsh road and trenching degrading environment. In some cases the forward body portion of the bit and/or pick can be made suitable for cutting conditions that are more abrasive and require a higher hardness forward portion, while in other cases the forward portion can be made suitable for cutting conditions that contain a gaseous environment and require a non-sparking forward portion.

SUMMARY

This disclosure relates generally to a bit for mining, trenching, and/or milling equipment. One implementation of the teachings herein is a bit that includes a substantially solid body comprising a truncated forward body portion and a generally cylindrical shank depending axially from a bottom of the forward body portion; a forward portion comprising a distal end opposite a forward end of the forward portion friction welded to a first interface of the truncated forward body portion, the first interface opposite the bottom of the forward body portion; and a bore axially extending from the forward end of the forward portion to a bore termination, the bore comprising one of a generally cylindrical sidewall and a tapered sidewall curving into the bore termination.

In another implementation of the teachings herein is a bit that includes a base comprising one of a generally cylindrical sidewall and a tapered sidewall; a forward end comprising an apex, a first parabolic side surface adjacent the apex, and one of a second parabolic side surface and a conical side surface adjacent the first parabolic side surface.

In yet another implementation of the teachings herein is a bit tip insert that includes a base comprising one of a generally cylindrical sidewall and a tapered sidewall; a forward end comprising an overlay including at least one of a polycrystalline diamond, industrial diamond, natural diamond, polycrystalline diamond composite material, and polycrystalline diamond compact material.

In yet another implementation of the teachings herein is a bit tip insert that includes a base comprising one of a generally cylindrical sidewall and a tapered sidewall; a forward end comprising an apex, a first parabolic side surface adjacent the apex, and one of a second parabolic side surface and a conical side surface adjacent the first parabolic side surface.

In yet another implementation of the teachings herein is a method of manufacture of a bit that includes welding a distal end of a forward portion to an interface of a truncated forward body portion of the bit at a weld joint; and machining an outer surface of the forward portion and a bore extending axially inwardly from a forward end of the forward portion.

In yet another implementation of the teachings herein is a method of manufacture of a bit that includes machining an outer surface of a forward body portion of the bit and a bore extending axially inwardly from a forward end of the forward body portion.

These and other aspects of the present disclosure are disclosed in the following detailed description of the embodiments, the appended claims and the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features, advantages, and other uses of the apparatus will become more apparent by referring to the following detailed description and drawings, wherein like reference numerals refer to like parts throughout the several views. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity.

FIG. 1 is a side elevation view of a prior art bit and a prior art bit tip insert, showing invisible internal elements in dotted lines;

FIG. 2 is an exploded side elevation view of the prior art bit and prior art bit tip insert, showing invisible internal elements in dotted lines;

FIG. 3 is a side elevation view of the prior art bit and prior art bit tip insert, showing invisible internal elements in dotted lines;

FIG. 4 is a side elevation view of the prior art bit and prior art bit tip insert, showing invisible internal elements in dotted lines;

FIG. 5 is an exploded side elevation view of a first embodiment of a bit, showing a truncated bit body and a forward end member, in accordance with implementations of this disclosure;

FIG. 6 is a side elevation view of the first embodiment of the bit, showing the bit body and the forward end member assembled together prior to friction welding, in accordance with implementations of this disclosure;

FIG. 7 is a side elevation view of the first embodiment of the bit, showing the bit body and the forward end member friction welded together, in accordance with implementations of this disclosure;

FIG. 8 is an exploded perspective view of the first embodiment of a bit, showing the truncated bit body and the forward end member, in accordance with implementations of this disclosure;

FIG. 9 is a perspective view of the first embodiment of the bit, showing the bit body and the forward end member assembled together prior to friction welding, in accordance with implementations of this disclosure;

FIG. 10 is a perspective view of the first embodiment of the bit, showing the bit body and the forward end member friction welded together, in accordance with implementations of this disclosure;

FIG. 11 is a side elevation view of the first embodiment of the bit, showing the bit body and the forward end member friction welded together, in accordance with implementations of this disclosure;

FIG. 12 is a perspective view of the first embodiment of the bit, showing the bit body and the forward end member friction welded together, in accordance with implementations of this disclosure;

FIG. 13 is a side elevation view of the first embodiment of the bit, showing the forward end member of the bit being machined to a frustoconical profile, in accordance with implementations of this disclosure;

FIG. 14 is a perspective view of the first embodiment of the bit, showing the forward end member of the bit being machined to a frustoconical profile, in accordance with implementations of this disclosure;

FIG. 15 is an exploded side elevation view of the first embodiment of the bit, showing the bit and a first embodiment of a bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure;

FIG. 16 is a side elevation view of the first embodiment of the bit, shown assembled with the first embodiment of the bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure;

FIG. 17 is a side elevation view of a second embodiment of a bit, showing a bit body and a forward end member friction welded together, the forward end member being machined, in accordance with implementations of this disclosure;

FIG. 18 is a perspective view of the second embodiment of the bit, showing the bit body and the forward end member friction welded together, the forward end member being machined, in accordance with implementations of this disclosure;

FIG. 19 is a side elevation view of the second embodiment of a bit, showing the forward end member of the bit being machined to a bulbous profile, in accordance with implementations of this disclosure;

FIG. 20 is a perspective view of the second embodiment of the bit, showing the forward end member of the bit being machined to a bulbous profile, in accordance with implementations of this disclosure;

FIG. 21 is an exploded side elevation view of the second embodiment of the bit, showing the bit and the first embodiment of the bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure;

FIG. 22 is a side elevation view of the second embodiment of the bit, shown assembled with the first embodiment of the bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure;

FIG. 23A is an exploded side elevation view of the first embodiment of the bit, the prior art bit tip insert, and the first embodiment bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure;

FIG. 23B is a side elevation view of the first embodiment of the bit, shown assembled with the first embodiment of the bit tip insert, showing the prior art bit tip insert superimposed on the bit in dotted lines, in accordance with implementations of this disclosure;

FIG. 24A is an exploded side elevation view of the second embodiment of the bit, the prior art bit tip insert, and the first embodiment bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure;

FIG. 24B is a side elevation view of the second embodiment of the bit, shown assembled with the first embodiment of the bit tip insert, showing the prior art bit tip insert and the forward end of the first embodiment bit superimposed on the second embodiment of the bit in dotted lines, in accordance with implementations of this disclosure;

FIG. 25 is a side elevation view of the second embodiment of the bit, shown assembled with the first embodiment of the bit tip insert, showing invisible internal elements in dotted lines and showing the silhouette of the forward end of the prior art bit and the silhouette of the prior art bit tip insert in dotted lines, in accordance with implementations of this disclosure;

FIG. 26 is a side elevation view of the first embodiment of the bit tip insert in accordance with implementations of this disclosure;

FIG. 27 is a detail view of Detail A of FIG. 26 of the first embodiment of the bit tip insert in accordance with implementations of this disclosure;

FIG. 28 is a detail view of Detail B of FIG. 26 of the first embodiment of the bit tip insert in accordance with implementations of this disclosure;

FIG. 29 is a side elevation view of the first embodiment of the bit tip insert in accordance with implementations of this disclosure;

FIG. 30 is a side perspective view of the first embodiment of the bit tip insert in accordance with implementations of this disclosure;

FIG. 31 is a side perspective view of the first embodiment of the bit tip insert in accordance with implementations of this disclosure;

FIG. 32 is a top elevation view of the first embodiment of the bit tip insert in accordance with implementations of this disclosure;

FIG. 33 is a side elevation view of the first embodiment of the bit tip insert in accordance with implementations of this disclosure;

FIG. 34 is a side elevation view of the first embodiment of the bit tip insert in accordance with implementations of this disclosure;

FIG. 35 is a side view of a plurality of bit assemblies mounted on a drum, showing the fourth embodiment of the bit and first embodiment of the bit tip insert, in accordance with implementations of this disclosure;

FIG. 36 is an exploded side elevation view of a third embodiment of a bit, the prior art bit tip insert, and the first embodiment bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure;

FIG. 37 is an exploded side elevation view of the third embodiment of the bit, showing the bit and the first embodiment of the bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure;

FIG. 38 is a side elevation view of the third embodiment of the bit, shown assembled with the first embodiment of the bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure;

FIG. 39 is a side elevation view of the third embodiment of the bit, shown assembled with the first embodiment of the bit tip insert, showing the prior art bit tip insert superimposed on the bit in dotted lines, in accordance with implementations of this disclosure; and

FIG. 40 is a side elevation view of the first embodiment of the bit tip insert brazed into the third embodiment of the bit in accordance with implementations of this disclosure.

DETAILED DESCRIPTION

Road mining, trenching, and milling equipment utilizes bits and/or picks traditionally set in a bit assembly. Bit assemblies can include a bit and/or pick retained within a bore in a base bock. Bit assemblies can also include a bit and/or pick retained by a bit holder and the bit holder retained within a bore in a bit holder block, hereinafter referred to as a base block. A plurality of the bit assemblies are mounted on an outside surface of a rotatable, cylindrical drum, typically in a herringbone, V-shape, or spiral configuration. A plurality of the bit assemblies can also be mounted on an endless chain and plate configuration or on an outer surface of a continuous chain. The combinations of bit assemblies have been utilized to remove material from the terra firma, such as degrading the surface of the earth, minerals, cement, concrete, macadam or asphalt pavement. Individual bits and/or picks, bit holders, and base blocks may wear down or break over time due to the harsh road and trenching degrading environment. In one embodiment, the bit body of the present disclosure includes a high compression and high tensile strength forward end member that is friction welded to the bit body and machined to the desired profile. In another embodiment, the bit body of the present disclosure is a unitary piece that includes a forward end member. The bit body also includes a cutting tip insert that is mounted in a recess in the forward end member of the bit body. The cutting tip insert can include a top portion that can be designed with a generally conical, parabolic, angular, and/or somewhat flattened radius style tip profile which provide for a better distribution of forces throughout the entire tip profile. In some cases the forward body portion of the bit and/or pick can be made suitable for cutting conditions that are more abrasive and require a higher hardness forward portion, while in other cases the forward portion can be made suitable for cutting conditions that contain a gaseous environment and require a non-sparking forward portion.

A prior art bit 10 and a prior art bit tip insert 12 are shown in FIGS. 1-4. The prior art bit 10 is substantially solid and comprises a body portion 14 and a shank 16 axially extending from a bottom of the body portion 14. The body portion 14 comprises a tapered upper body portion 18 axially depending from a forward end 20 of the body portion 14. Subjacent the upper body portion 18 is a mediate body portion 22 that generally slopes axially and radially outwardly to a radially extending generally arcuate tire portion 24 that terminates at a generally annular back flange 26 which denotes the bottom of the body portion 14.

The shank 16 comprises a first segment 28 that slopes axially inwardly from the back flange 26 to a generally cylindrical second segment 30. The second segment 30 axially extends from the first segment 28 to a shoulder 32 that slopes axially inwardly from the second segment 30 to a generally cylindrical third segment 34. The third segment 34 axially extends from the shoulder 32 to a tapered distal portion 36 adjacent a distal end 38 of the shank 14. The third segment 34 comprises an annular groove 40 adjacent the tapered distal portion 36 of the shank 14 where it can be engaged by a bit retainer (not shown) or the like.

The upper body portion 18 includes a tapered bore 42 that axially extends from the forward end 20 of the body portion 14 to a bore termination 44 disposed within the upper body portion 18. The bore 42 provides a space for receiving a complementary shaped tapered outer sidewall or body 46 of the prior art bit tip insert 12. The prior art bit tip insert 12 comprises a base 48 and a conical tip 50 at a forward end 52 of the bit tip insert 12. The base 48 comprises the complementary shaped tapered outer sidewall or body 42 and a cylindrical distal portion 54 subjacent the outer sidewall or body 42 that extends to the distal end 56 of the bit tip insert 12. The bit tip insert 12 is adapted to be mounted (FIG. 3) and brazed (FIG. 4) in the complementary shaped bore 42 of the body portion 14.

This prior art bit 10 has two design flaws in the attached bit tip insert 12 region of the bit, as shown and described with reference to FIG. 4. The thickness at sector “F” of the bit 10 is generally determined by a thickness value that allows bit penetration into the material being removed. If sector “F” is too wide, penetration of the bit is reduced. The thickness of the frontal portion of the bit 10 at location “F” is too narrow to withstand a high value sideload at location “E”. The applied sideload at location “E” causes “B” to push away due to less sidewall support at location “B” and due to the pivot action at location “C” acting as a fulcrum lever. When a small movement occurs at location “B”, a fulcrum force at location “C” adds to the force applied at location “E” to cause the braze joint 58 (FIG. 4) to fail. Braze joint failure causes much accelerated failure of the bit itself.

Referring to FIGS. 5-16, 23A, and 23B, a first embodiment of a rotatable or non-rotatable substantially solid bit or tool 60 comprises a body portion 62, which can be made of steel 15B37, 4140, 4340, or other similar suitable materials, and a shank 64 axially extending from a bottom of the body portion 62. The body portion 62 comprises a generally cylindrical or outwardly tapered upper body portion 66 axially depending from an interface 68 (FIGS. 5 and 8), such as a flat annular or generally cylindrical surface in this exemplary implementation, that defines a forward end 70 (FIGS. 5 and 8) of the body portion 62. The upper body portion 66 is generally cylindrical in this exemplary implementation. Subjacent the upper body portion 66 is a mediate body portion 72 that generally slopes axially and radially outwardly to a radially extending generally arcuate tire portion 74 that terminates at a generally annular back flange 76 which denotes the bottom of the body portion 62.

The shank 64 comprises a first segment 78 that slopes axially inwardly from the back flange 76 to a generally cylindrical second segment 80. The second segment 80 axially extends from the first segment 78 to a shoulder 82 that slopes axially inwardly from the second segment 80 to a generally cylindrical third segment 84. The third segment 84 axially extends from the shoulder 82 to a tapered distal portion 86 adjacent a distal end 88 of the shank 64. The third segment 84 comprises an annular groove 90, which in this illustrated embodiment includes a flat inner surface 92 but can also have an arcuate or other shaped surface in other embodiments, adjacent the tapered distal portion 86 of the shank 64 where it can be engaged by a bit retainer (not shown) or the like.

A high compression and high tensile strength forward end member or nose member 94, which can be made of steel 4140, 4340, or other similar suitable materials and/or high wear, abrasive resistant, high strength alloy steel, comprises a nose body 96 that axially extends from a nose forward end 98 to an interface 100 (FIG. 5), such as a flat annular or generally cylindrical surface in this exemplary implementation, defining a nose distal end 102 (FIGS. 5 and 8) of the nose member 94. The interface 100 of the nose member 94 is friction welded to the interface 68 of the body portion 62 of the bit 60, which forms a friction welded joint 104 between the nose member 94 and the body portion 62. In one embodiment, the body portion 62 can be made of a lesser strength steel, such as 15B37 steel which is the most commonly used steel for conical bits in mining, trenching, and highway construction.

The nose member 94 is machined after it has been friction welded to the body portion 62. A machining tool insert 106, shown in various locations as the machining tool insert 106 moves axially forward along the outer surface of the nose member 94 as the bit 60 is rotated counter clockwise, machines the outer surface of the nose member 94 to the desired profile, which in this illustrated embodiment comprises a frustoconical profile. A drill and a boring bar (not shown) are used to machine a recess or cavity 108 at the nose forward end 98 of the nose member 94. The nose member 94 is machined using the drill to comprise the recess or cavity 108 extending axially inwardly from the nose forward end 98 to a recess termination 110 disposed within the nose member 94. The boring bar machines the recess or cavity 108 to finish the profile of the hole 108. An annular sidewall 114 (FIGS. 16, 23A, and 23B) surrounding the recess 108 comprises a weak region of the nose member 94 of this first embodiment, however, the 4340 steel of the nose member 94 at the same hardness of other steels, such as 15B37 type steels, will have about 50% greater tensile strength and yield strength. In this illustrated embodiment, the recess 108 includes a tapered sidewall 112 that curves into the recess termination 110 which is generally flat, as shown in FIGS. 15 and 16. The recess 108 provides a space for receiving a complementary shaped tapered outer sidewall or body 122 of a first embodiment of a bit tip insert 120, which in this embodiment is made of tungsten carbide.

The first embodiment of the bit tip insert 120, shown in FIGS. 15, 16, and 21-34, comprises a base 124 and a tip 126 at a forward end 128 of the bit tip insert 120. The tip profile, which comprises a full tip radius or angular tip profile, is usually made to the same included angle of the attack angle 144 (FIG. 29) of the bit holder or base block. The tip profile of the forward end 128 of the bit tip insert 120 includes a parabolic curved section 130 below an apex of the tip insert 120 and a parabolic or conical section 132 adjacent the parabolic curved section 130. In other embodiments, the forward end 128 of the bit tip insert 120 can also have a frustoconical shape, a flat generally cylindrical puck shape, a parabolic ballistic shape, a conical shape, an angular shape, and/or an arcuate shape.

The tip profile of the bit tip insert 120 determines its ability to withstand applied forces. The tip geometry also determines the rate of tip wear. The greater the surface area of the tip portion, the more vertical force, rather than horizontal force, is applied to the tip, as shown in FIG. 34. When two different tip geometries are used in nearly the same highly abrasive, high compressive loading cutting conditions, the more robustly constructed tip geometry will outperform the other tip profile designs for various reasons: (1) a smaller tip profile does not contain a sufficient cross-sectional tip configuration to withstand variable angular impacts for removal of high compressive rock formations; (2) the narrow tip profile, by nature of its design, has a smaller tip radius and/or smaller tip profile which is followed by a transitioning sidewall that enlarges as it axially descends to a maximum diameter of the bit tip insert at about mid-length; (3) the narrow tip profile, due to its design, has poor powder processing issues when the insert is first formed during the powder pressing cycle, the forces, both horizontal and vertical, are more horizontal than vertical and not equally distributed, and the majority of the upper punch forces are applied well below the apex of the bit tip insert tip profile because the tonnage of the press is mostly consumed by the total bit tip insert surface area by the punch that forms the tip profile; and (4) a small tip profile will wear away more rapidly and develop a tip profile that approximates the same angle that the bit and/or tool engages the tierra firma or macadam, unless the holder bore wear and/or base block bore wear causes a different angle to develop.

The base 124 comprises the complementary shaped tapered outer sidewall or body 122 of the bit tip insert 120 that is adapted to be mounted in the complementary shaped recess 108 of the nose member 94. The base 124 comprises a small flat bottom 134 at a distal end 136 of the bit tip insert 120, which in this illustrated embodiment has a nominal ¼ inch diameter. The tapered outer sidewall 122 of the base 124 includes an arcuate portion 138 adjacent the distal end 136 that curves into the small flat bottom 134 of the base 124 of the bit tip insert 120, which is complementary shaped to the tapered sidewall 112 and recess termination 110 of the recess 108. Better heat penetration is provided to the base 124 of the bit tip insert 120. In this illustrated embodiment, which includes a frustoconical nose profile nose member 94, the radial stress occurring at location 116 (FIG. 23B) of the extended bit tip insert 120 will create greater radial stress on the sidewall 114 of the nose forward end 98 and will lead to premature bit failure.

Referring to FIGS. 26-29, the tapered outer sidewall 122 of the base 124 comprises a first plurality of circumferentially spaced protrusions 140 adjacent the tip 126 and a second plurality of circumferentially spaced protrusions 142 adjacent the distal end 136 of the base 124, shown in detail in FIGS. 27 and 28. The first plurality of circumferentially spaced protrusions 140 and the second plurality of circumferentially spaced protrusions 142 adapted to provide for precision spacing between the parts, and both self-centering and self-aligning of the tip insert 120 in the recess 108 of the nose member 94 of the bit 60. In this exemplary implementation of the first embodiment, preferably the tapered outer sidewall 122 of the base 124 is sufficiently spaced from the tapered sidewall 112 of the recess 108 of the nose member 94 to allow braze material to flow between the parts and establish the braze thickness when the bit tip insert 120 is brazed in the recess 108 of the nose member 94 of the bit 60. The radius profile of the arcuate portion 138 of the bit tip insert 120 allows capillary action and allows melted flux material to flow freely from the base region of the bit tip insert 120 and the bottom of the recess 108 of the nose member 94 thereby producing a stronger braze joint.

When induction heating a steel member, the magnetic flux lines develop within the coil of the induction heating system. The magnetic flux lines excite the iron in the steel and create high heat in the steel member which then melts the braze material. The combination of the heated steel and the melted braze material transfers heat sufficiently to the tungsten carbide bit tip insert which then attaches the steel-braze-carbide together.

Referring to FIGS. 17-22, 24A, 24B, 25, and 35, a second embodiment of a rotatable or non-rotatable substantially solid bit or tool 150 is substantially the same as the bit 60 of the first embodiment with an exception that the machining tool insert 106 machines the outer surface of the nose member 94 to the desired profile, which in this illustrated embodiment comprises a bulbous profile 152 (FIGS. 24B and 25) that provides greater strength than the frustoconical profile. The bulbous profile design allows lesser strength steel, such as 15B37 steel, to be used for the nose member in a bit body with lesser tensile strength and/or yield strength. The bit tip insert 120 is then brazed in the recess 108 of the nose member 94 of the bit 150. The bulbous profile 152 (FIGS. 24B and 25) of the bit body 190 can be a unitary design or can be made as a two-piece friction welded design as described with reference to the first embodiment of bit 60. A plurality of the bit assemblies comprising the second embodiment of the bit 150 and the first embodiment of the bit tip insert 120, mounted on an outside surface of a rotatable, cylindrical drum, are shown in FIG. 35.

Referring to FIG. 24A, apex A-A is greater than B-B along any portion of dotted lines D, D. The bulbous design increases the thickness at “C” of the annular sidewall 114 surrounding the recess 172 without affecting bit penetration. The thickness at “C” in FIGS. 24B and 25 is determined by the tensile strength of the steel and develops a larger and stronger profile than the frustoconical profile 118 (FIGS. 24B and 25) of bit 160 in FIG. 23, shown by dotted lines D, D in FIGS. 24A and 25. The wall thickness at “F” for the bulbous design 152 is the same or less than the wall thickness at “F” for the frustoconical design 118.

Referring to FIG. 25, the bulbous or forward bit profile 152 that increases the thickness at “C” develops an increased surface length at H-H and J-J adjacent a forward end of the bit profile to withstand greater cutting forces at location “E’. A force applied at location “E” creates a tensile component force along H-H and a compression component force along J-J.

Referring to FIGS. 36-40, a third embodiment of a rotatable or non-rotatable substantially solid bit or tool 160 comprises a body portion 162, which can be made of steel 15B37, 4140, 4340, or other similar suitable materials, and a shank 164 axially extending from a bottom of the body portion 162. The body portion 162 comprises, in this illustrated embodiment, an outwardly tapered upper body portion 166 axially depending from a forward end 168 of the body portion 162. In other embodiments, the upper body portion 166 can be generally cylindrical or have other shapes. Subjacent the upper body portion 166 is a mediate body portion 170 that generally slopes axially and radially outwardly to a radially extending generally arcuate tire portion 172 that terminates at a generally annular back flange 174 which denotes the bottom of the body portion 162.

The shank 164 comprises a first segment 176 that slopes axially inwardly from the back flange 174 to a generally cylindrical second segment 178. The second segment 178 axially extends from the first segment 176 to a shoulder 180 that slopes axially inwardly from the second segment 178 to a generally cylindrical third segment 182. The third segment 182 axially extends from the shoulder 180 to a tapered distal portion 184 adjacent a distal end 186 of the shank 164. The third segment 182 comprises an annular groove 188, which in this illustrated embodiment includes a flat inner surface 190 but can also have an arcuate or other shaped surface in other embodiments, adjacent the tapered distal portion 188 of the shank 164 where it can be engaged by a bit retainer (not shown) or the like.

The outer surface of the upper body portion 166 is machined using the machining tool insert 106, as shown in FIGS. 13, 14, and 17-20. The drill and the boring bar (not shown) are used to machine a recess or cavity 192 (FIGS. 36 and 37) at the forward end 168 of the body portion 162. The body portion 162 is machined using the drill to comprise the recess or cavity 192 extending axially inwardly from the forward end 168 to a recess termination 194 disposed within the upper body portion 166. The boring bar machines the recess or cavity 192 to finish the profile of the hole 192. In this illustrated embodiment, the recess 192 includes a tapered sidewall 196 that curves into the recess termination 194 which is generally flat, as shown in FIGS. 36-38. The recess 192 provides a space for receiving the complementary shaped tapered outer sidewall or body 122 of the first embodiment of the bit tip insert 120, which in this embodiment is made of tungsten carbide.

In an exemplary implementation of this illustrated embodiment, the bit 160 is made of 4340 steel. The bit tip insert 120 is brazed in the recess 192 of the body portion 162 using HI-TEMP 548 (“HT-548”) braze material. When the brazing temperature reaches approximately 1800° F., the molten braze infiltrates by capillary action into the interstitial outer region of the tungsten carbide insert, thereby forming a deeper and larger surface area bond with the tungsten carbide insert, which contains tungsten, carbon, and cobalt in this exemplary implementation. When using carbon steel such as 15B37 for the bit, the braze material only bonds to the mating steel surface for which it has a strong bond relationship and there is no significant sub-surface attachment of the HT-548 braze material and the 15B37 steel.

The braze joint 198, shown in FIG. 40, strength improves significantly when 4340 steel is used in place of 15B37 steel to join a tungsten carbide insert into the pocket or hole 192 of the bit body portion 162. The addition of a nickel alloy, and to a lesser extent the addition of molybdenum and chromium, to the 4340 steel of the bit 160 increases the braze joint strength by a doubling of strength value.

The tensile strength of the 4340 steel and of the 15B37 steel, in this case, have similar tensile strength values, except that the 15B37 steel requires a higher hardness to achieve a similar tensile strength as the 4340 steel.

The 4340 steel of the bit 160 comprises 1.55-2.00% nickel alloy along with a small amount of molybdenum and chromium alloys. The 1.55-2.00% nickel alloy in the 4340 steel improves the attachment to the 6% nickel alloy in the low cost HT-548 braze material alloy, which is significantly lower in cost than silver braze alloy.

Referring to FIG. 40, force was applied at location “A” to determine when braze joint failure initiation would occur at location “B” using HT-548 braze material. The 15B37 steel bit would have braze joint failure initiation when 43,355 pounds of force was applied at location “A”, while the 4340 steel bit would have braze joint failure initiation when 89,410 pounds of force was applied at location “A.” The improvement of the attachment strength between the 4340 steel bit and the tungsten carbide insert with a cobalt binder using HT-548 braze material alloy and between 15B37 steel and HT-548 braze material alloy with the same tungsten carbide chemistry in the insert is about at least two fold using the 4340 steel.

As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X includes A or B” is intended to mean any of the natural inclusive permutations. That is, if X includes A; X includes B; or X includes both A and B, then “X includes A or B” is satisfied under any of the foregoing instances. In addition, “X includes at least one of A and B” is intended to mean any of the natural inclusive permutations. That is, if X includes A; X includes B; or X includes both A and B, then “X includes at least one of A and B” is satisfied under any of the foregoing instances. The articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Moreover, use of the term “an implementation” or “one implementation” throughout is not intended to mean the same embodiment, aspect or implementation unless described as such.

While the present disclosure has been described in connection with certain embodiments, it is to be understood that the present disclosure is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law. 

1. A bit comprising: a substantially solid body comprising a truncated forward body portion and a generally cylindrical shank depending axially from a bottom of the forward body portion; a forward portion comprising a distal end opposite a forward end of the forward portion friction welded to a first interface of the truncated forward body portion, the first interface opposite the bottom of the forward body portion; and a bore axially extending from the forward end of the forward portion to a bore termination, the bore comprising one of a generally cylindrical sidewall and a tapered sidewall curving into the bore termination.
 2. The bit of claim 1, further comprising: a bit tip insert comprising a base complementary shaped to the bore of the forward portion, the base of the bit tip insert adapted to be mounted and brazed within the bore of the forward portion.
 3. The bit of claim 2, further comprising: a forward end of the base of the bit tip insert comprising an overlay including at least one of a polycrystalline diamond, industrial diamond, natural diamond, polycrystalline diamond composite material, and polycrystalline diamond compact material.
 4. The bit of claim 2, further comprising: the overlay comprising an apex, a first parabolic side surface adjacent the apex, and one of a second parabolic side surface and a conical side surface adjacent the first parabolic side surface.
 5. The bit of claim 2, further comprising: a first plurality of circumferentially spaced protrusions adjacent a forward end of the base of the bit tip insert; and a second plurality of circumferentially spaced protrusions adjacent a distal end of the bit tip insert.
 6. The bit of claim 2, further comprising: one of a generally cylindrical sidewall and a tapered sidewall of the base of the bit tip insert; an arcuate portion subjacent one of the generally cylindrical sidewall and the tapered sidewall; and a non-planar surface at a distal end of the bit tip insert, the non-planar surface adjacent the arcuate portion.
 7. The bit of claim 6, wherein the non-planar surface comprises a nominal ¼ inch diameter.
 8. The bit of claim 4, further comprising: a generally cylindrical side surface adjacent one of the second parabolic side surface and the conical side surface.
 9. The bit of claim 1, the forward portion comprising one of a frustoconical outer surface and a bulbous outer surface.
 10. The bit of claim 1, further comprising: a second interface at a distal end of the forward portion, the second interface of the forward portion is one of friction welded, inertia welded, and spin welded to the first interface of the forward body portion. 11-25. (canceled)
 26. A bit tip insert comprising: a base comprising one of a generally cylindrical sidewall and a tapered sidewall; a forward end comprising an apex, a first parabolic side surface adjacent the apex, and one of a second parabolic side surface and a conical side surface adjacent the first parabolic side surface.
 27. The bit tip insert of claim 26, further comprising: a first plurality of circumferentially spaced protrusions disposed on one of the generally cylindrical sidewall and the tapered sidewall of the base adjacent the forward end; and a second plurality of circumferentially spaced protrusions disposed on one of the generally cylindrical sidewall and the tapered sidewall of the base adjacent a distal end of the bit tip insert.
 28. The bit tip insert of claim 26, further comprising: an arcuate portion subjacent one of the generally cylindrical sidewall and the tapered sidewall; and a non-planar surface at a distal end of the bit tip insert, the non-planar surface adjacent the arcuate portion.
 29. The bit tip insert of claim 28, wherein the non-planar surface comprises a nominal ¼ inch diameter.
 30. The bit tip insert of claim 26, further comprising: a generally cylindrical side surface adjacent one of the second parabolic side surface and the conical side surface. 31-36. (canceled)
 37. A bit comprising: a substantially solid body portion and a generally cylindrical shank depending axially from a bottom of the solid body; and a bore axially extending from a forward end of the body portion to a bore termination, the bore comprising one of a generally cylindrical sidewall and a tapered sidewall curving into the bore termination.
 38. The bit of claim 37, further comprising: a bit tip insert comprising a base complementary shaped to the bore of the body portion, the base of the bit tip insert adapted to be mounted and brazed within the bore of the body portion.
 39. The bit of claim 38, further comprising: a forward end of the base of the bit tip insert comprising an apex, a first parabolic side surface adjacent the apex, and one of a second parabolic side surface and a conical side surface adjacent the first parabolic side surface.
 40. The bit of claim 38, further comprising: a forward end of the base of the bit tip insert comprising an overlay including at least one of a polycrystalline diamond, industrial diamond, natural diamond, polycrystalline diamond composite material, and polycrystalline diamond compact material, the overlay comprising an apex, a first parabolic side surface adjacent the apex, and one of a second parabolic side surface and a conical side surface adjacent the first parabolic side surface.
 41. The bit of claim 38, further comprising: a first plurality of circumferentially spaced protrusions adjacent a forward end of the base of the bit tip insert; and a second plurality of circumferentially spaced protrusions adjacent a distal end of the bit tip insert.
 42. The bit of claim 38, further comprising: one of a generally cylindrical sidewall and a tapered sidewall of the base of the bit tip insert; an arcuate portion subjacent one of the generally cylindrical sidewall and the tapered sidewall; and a non-planar surface at a distal end of the bit tip insert, the non-planar surface adjacent the arcuate portion.
 43. The bit of claim 42, wherein the non-planar surface comprises a nominal ¼ inch diameter.
 44. The bit of claim 40, further comprising: a generally cylindrical side surface adjacent one of the second parabolic side surface and the conical side surface.
 45. The bit of claim 37, the body portion comprising one of a frustoconical outer surface and a bulbous outer surface. 46-49. (canceled) 